Abstract

This study was conducted to evaluate the compositional and sanitary
quality of raw milk produced by smallholder dairy farmers (SHDFs) in
Lusaka province of Zambia. Compositional and sanitary quality of milk
was determined by assessing the added water and milk components and
Total Bacterial Count (TBC) and Total Coliforms Count (TCC),
respectively. Altogether, 83 raw milk composite samples were collected
from 83 SHDFs and analyzed at the University of Zambia, School of
Veterinary Medicine Public Health Laboratory. Milk composition and added
water were determined using a LactiCheck ® Ultrasonic
Milk Analyzer (Page & Pedersen International Ltd, USA). Total bacterial
count (TBC) and TCC were determined by culturing the raw milk samples on
Standard Plate Count Agar (SPC) and Violet Red Bile Glucose Agar (VRB),
respectively.

Results showed that butter fat (BF) for raw milk from 23 out of 83 farms
(27.7%) was below recommended standards and legal minimum limit of 3.2%
fat. Solid Not Fat (SNF) for raw milk from 26 out of 83 farms (31.3%)
was below recommended standards and legal minimum limit of 8.3%. Density
of milk for 28 out of 83 farms (33.7%) was also below recommended
standards (1.025g/cm3). It was also observed that 26 out of
83 farmers (31.3%) had added some quantity of water varying from 9.46 -
34.3 % to their raw milk. It is worth mentioning that all milk samples
which were found to be adulterated with water had low density, low BF
and low SNF content. Total Bacterial Count (TBC) ranged from 445 to 2.6
x 106 cfu/ml and milk from 5 out of 83 farms (6.02%) had TBC
above the recommended national standards and legal maximum required
limit of 200,000 cfu/ml. Total coliforms count (TCC) ranged from 100 to
100,000 cfu/ml and milk from 4 out of 83 farmers (4.82%) had TCC above
the maximum national recommended limit of 50,000 cfu/ml. The study
concluded that sanitary quality of milk produced by SHDFs in Lusaka
province of Zambia, as far as bacterial contamination is concerned was
within acceptable standards as opposed to the findings in many other
countries in the region including an earlier report from Zambia, where
high bacterial contamination and poor quality of raw milk has been
reported. The current good results in Zambia found in this study might
be attributed to the recent emphasis and support towards clean hygienic
production of milk and the higher price paid by milk processing
companies for raw milk with low bacteria content and dry climatic
conditions and absence of zero-grazing practice. Added water in some
milk samples indicate that some SHDFs are engaged in fraudulent
activities of milk adulteration and need to be regulated. It is
therefore important that the compositional and sanitary quality of raw
milk produced by SHDFs is monitored on a regular basis.

Introduction

Milk is a major component of human diet all over the world (Gran et al 2002). It is an important source of nutrients required for
growth in infants and for maintenance of health in adults. Raw cow milk
is composed of approximately 87.2 % water, 3.7 % fats, 3.5% protein,
4.9% lactose 0.7% ash and has a pH 6.8 (Olatunji et al 2012). Due to its high
moisture content, pH which is close to neutral and the diversity of
nutrients, milk is a good growth medium for several types of
microorganisms (Acuri et al 2006). Microorganisms can enter
into milk during milking stage, storage or transportation to the market
(Garedew et al 2012). These microorganisms can come from the
environment, animals being milked, milkers or from equipment used in the
milking parlour (Gran et al 2002). Once they enter into milk,
microorganisms can multiply and cause changes to its quality and safety
value. If pathogenic microorganisms are involved, they can cause harm to
consumers by causing human illness and disease (Barros et al
2011).

Milk TBC is a major factor in determining its hygienic quality (Khan et
al 2008). It indicates udder infection and the level of
cleanliness of udders, milkers and milking equipment during milk
production. It also indicates condition under which milk is stored and
transported (Karikari et al 1998). Raw milk with high
microbial load has poor keeping quality and products manufactured from
it are of inferior quality and have a reduced shelf life (Hayes et al 2011).

Coliforms are almost always present in raw milk but withgood
methods of production their number can bekept low (Boor et al 1998). The presence of these microorganisms in milk and milk products
is an indication ofunsanitary production and improper handling
of eithermilk or milk utensils and is generally associated
with fecal contamination (Boor et al 1998). Kagkli et al
(2006) showed that in addition to faecal contamination, other factors
such as milking wet udders, inadequate cooling of milk and udder
infection are the main sources of coliforms in milk. Escherichia
coli (E. coli) is the most commonly isolated coliform from
milk in the clinical laboratory (Ahmed and Salam 1991). In immune
compromised individuals, for example HIV patients, some coliforms can
cause a wide range of infections as opportunisticpathogens
(Boor et al 1998).

Water is the most common adulterant in milk which is often added to milk
by unscrupulous milk dealers who want to increase the volume in order to
earn easy money (Ombui et al 1995). Addition of water to milk
reduces its nutritive value and if the water added is contaminated,
there is a health risk posed to consumers (Kandpal et al
2012). Such contaminated milk can be harmful to consumers if consumed
raw and if it is processed, the products have reduced shelf life
(Kandpal et al 2012).

The smallholder dairy farming industry in many African countries,
including Zambia, is important because it plays a significant role in
ensuring food security and alleviation of poverty. It provides
households with the much required employment, income generation and
nutritious food (Pandey, 2014). Smallholder Dairy Farmers (SHDFs) in
Zambia have improved their milk production volumes as a result of
assistance from government and Non Governmental Organizations (NGOs).
Collection and transportation of milk which historically has been a
serious problem for SHDFs is no longer a limiting factor in Zambia
particularly in peri-urban areas (Yambayamba and Zulu 2011). Zambia’s
domestic milk consumption is approximately 3.0 x 108 litres
per annum and it is estimated that half of this requirement is produced
by SHDFs (Valeta 2004). This study was aimed at assessing the public
health aspects of milk from SHDFs by evaluating the wholesomeness (water
adulteration), safety (microbiological hazards) and compositional
quality of milk produced by SHDFs.

Materials and methods

The study was done in Lusaka Province of Zambia during the months of
January and February 2014 using a cross-sectional study design. Records
at the milk collection centres (MCCs) and the Dairy Association of
Zambia (DAZ) were used to create a sampling frame from which 83 SHDFs
who participated in the study were randomly selected. Twenty six farmers
belonged to Palabana dairy scheme MCC, 30 farmers to Mapepe dairy
co-operative society MCC and 27 farmers to Lusaka west farming block.
Farmers from these areas were selected to participate in the study
because that is where the majority of SHDFs in Lusaka Province are
found. Sampling units were individual smallholder dairy farms. From the
bulk raw milk of each of the 83 selected farms, 50 ml was collected
aseptically in sterile sample bottles as milk was being delivered to
MCCs. The collected samples were stored in an ice packed cooler box and
transported to University of Zambia, School of Veterinary Medicine
Public Health laboratory and analyzed the same day.

Compositional quality

Composition of the 83 raw milk samples was analyzed using a LactiCheck®
Ultrasonic Milk Analyzer. Each milk sample was analyzed by getting 20 ml
of the milk sample at room temperature, thoroughly mixing it in a test
tube and then transferred into the sample cup. The sample cup was placed
below the aspiration tube of the LactiCheck® Ultrasonic Milk
Analyzer connected to power and the start button was pressed to start
the analysis. Analysis was done in about 85 seconds and the results of
different parameters displayed on the screen of the LactiCheck®
Ultrasonic Milk Analyzer were noted. The parameters estimated were:
added water, BF, SNF, protein and lactose in percentage, density in
grams per cubic centimeters and freezing point in degree celsius.

Sanitary quality

Standard plate count (SPC) method was used to determine TBC in milk
samples. Each of the 83 milk samples were aseptically diluted into three
different dilutions of 1:10. 1:100 and 1:1,000 and plated in duplicates
on standard plate count agar and incubated for 48 hours at 32°C. Then
using a colony counter, bacteria (or clusters) that grew and became
visible colonies were counted and expressed as number of colony forming
units per milliliter (cfu/ml) of milk. To determine TCC, in the same way
as for TBC, the 83 raw milk samples were diluted into three dilutions of
1:10. 1:100 and 1:1,000 and plated in duplicates on Violet Red Bile
Glucose Agar, incubated at 32°C for 48 hours then similarly counted the
colonies using a colony counter.

Statistical analysis

Data generated from testing the 83 samples of raw milk was entered into
Microsoft excel then transferred to SPSS version 20 for analysis. Means
and percentages of milk parameters were calculated. To determine
association between added water and density and added water and SNF,
correlation coefficient test was used.

Results

Compositional quality

Table 1 presents a summary of test results on milk composition. Butter
Fat (BF) for milk from 23 out of 83 farms (27.7%) was below national
recommended standards (3.2% fat) and SNF of milk from 26 out of 83 farms
(31.3%) was below recommended standards (8.3%). Density of milk for 28
out of 83 farms (33.7%) was below recommended standards (1.025g/cm3)
and milk from 26 out of 83 farms (31.3%) had added some quantity of
water varying from 9.46 to 34.3% of the milk volume. The mean BF content
of milk was 3.9%, SNF 9.3 %, protein 3.7 %, lactose 5.2% and water
content 86.8%

Table 1.
Summary of results for milk composition tests

Milk component

Minimum

Maximum

Mean

Butter Fat (%)

2.5

6.9

3.9

Solid Not Fat (%)

7.3

10.0

9.3

Protein (%)

2.3

3.8

3.7

Lactose (%)

3.8

5.6

5.2

Water (%)

90.2

83.1

86.8

Correlation coefficient tests, at a significance level of 0.01 (Table 2
and Figures 1 and 2) showed that there was a strong negative association
(r = -.959; p=0.001) between added water and milk density. There was
also a strong negative association between added water and SNF (r =
-.916; p=0.001).

Table 2.
Summary of results for correlation coefficient tests

SNF

Density (g/cm3)

Water

Pearson Correlation

-0.916

-0.959**

Sig. (2-tailed)

0.001

0.001

N

83

83

** Correlation is significant at the 0.01 level (2-tailed)

Figure 1. Correlation between
added water and density

Figure 2. Correlation between
added water and SNF

Bacteriological quality

Results on TBC (Table 3) showed that raw milk from 5 out of the 83 farms
(6.02%) was above the maximum and legally accepted number in Zambia (200,000
cfu/ml of raw milk). Total Coliforms Count (TCC) of milk from 4 out of 83
farms (4.8%) did not conform to recommended standards (50,000 cfu/ ml of raw
milk).

Table 3.
Summary of results for bacteriological tests

Minimum

Maximum

Mean

TBC (cfu/ml)

445

2.6 x 106

9.3 x 104

TCC (cfu/ml)

100

1.0 x 105

8.9 x 103

Discussion

Production of raw milk of good compositional and sanitary quality by farmers
is important to milk processing companies, milk consumers and the farmers
themselves. This is so because raw milk of poor compositional and sanitary
quality has reduced processing properties and processed milk and milk
products made from such raw milk have a reduced shelf life (Oliver et al
2005). For consumers, consumption of milk contaminated with pathogenic
bacteria can lead to diseases. For SHDFs, producing milk of good quality is
important because milk processing companies pay farmers in accordance with
the compositional and sanitary quality of raw milk delivered to them
(Yambayamba and Zulu 2011). Thus good quality means more income to the
farmer.

On composition, the study found that Butter Fat (BF) for raw milk from 27.7% farms was below recommended standards and minimum legal limit of 3.2%
fat. Solid Not Fat (SNF) at 31.3% farms was below recommended standards and
minimum legal limit of 8.3%. Density for raw milk at 33.7% farms was below
recommended standards of 1.025 g/cm3. On adulteration of milk
with water, 31.3% farms had added some quantity of water varying from 9.46 -
34.3 % to their raw milk. It is worth to mention that all milk samples which
were found to be adulterated with water had low density, low BF and low SNF
content. It was therefore concluded that water adulteration was the most
probable cause of low density, low BF and low SNF in some milk samples. This
was supported by the results of correlation coefficient tests where a strong
negative association between added water and density (r = -0.959; p=0.001)
and between added water and SNF (r = -0.916; p=0.001) were found. In similar
studies done in other countries, Donkor et al (2007) and
Karimuriboet al (2005) found 18% farmers in Ghana and 5% farmers
in Kilosa district, Tanzania respectively had added water to their milk. In
Kenya, Mwangi et al (2000) found 13% of raw milk samples from
Kiambu and Nairobi were adulterated with water. In comparison, these
findings from other countries were lower than the 31.3% of water adulterated
milk in Zambia as found by this study. When there is high demand for milk,
unscrupulous milk dealers sometimes add water to milk in order to increase
its volume so that they can earn easy money. Addition of water to milk
should be avoided because it reduces the nutritive value of milk, and if
contaminated, it poses a health risk to consumers (Kandpal et al
2012) and need stiffer penalty on milk adulteration. However the composite
compositional value of milk was within the recommended standards.

For TBC and TCC, the study found that milk produced by 94% of the SHDFs
conformed to the recommended standards. Milk from only 5 farmers (6.02%) had
TBC above the recommended standards and maximum legal limit of 200,000
cfu/ml of raw milk while milk from 4 farmers (4.82%) had TCC above the
maximum recommended limit of 50,000 cfu/ml of raw milk. Our microbiological
findings are similar to the findings by Yambayamba and Zulu (2011) who
reported TBC which ranged from 44,333 to 234,583 cfu/ml but contrary to the
findings by Pandey et al (1996) who reported TBC ranging from log
7.66 - 9.15 cfu /ml and TCC ranging log 6.18 – 7.20 cfu /ml both studies
from Zambia. In similar studies conducted in other countries in the region,
very high bacterial counts were found in raw milk. In Malawi, Shitandi and
Kihumbu (2004) found a high mean TBC of 3.4 x 107 cfu/ml of raw
milk. In Tanzania, Kivaria et al (2006) found a high TBC of 8.2 X
106 cfu/ml of raw milk in the Dar es Salaam region while in
Kilosa district Karimuribo et al (2005) found 13.4% of milk had
TBC which did not conform to recommended standards of that country. In
Mbarara, the major milk producing region in Uganda, Grimaud et al
(2007), found a high bacterial load of 2 x 106 cfu/ml of raw in a
survey on milk quality done in 2004. Mwangi et al (2000) in Kiambu
and Nairobi, Kenya found 82 % and 58 % of raw milk samples did not meet
recommended standards for TBC and coliforms count respectively even when
their (EAC) standards of TBC is extremely poor (2x106 cfu/ml).
They found TBC 1.49x109 cfu/ml and coliforms count 1.49 x 106
cfu/ml. In Swaziland Fakudze and Dlamini (2001) found high TBC (> 1 x 107
cfu/ml of raw milk) and high coliforms count (> 7 x 104 cfu/ml of
raw milk). In the most recent study, Kanyeka (2014) in Tanzania found 85.7%
of the raw milk samples had significantly higher TBC than recommended level
of 2x106 cfu/ml by EAC standards and concluded that quality of
raw milk was very poor.

The positive results on TBC and TCC in our study might be attributed to the
recent emphasis and massive support towards clean hygienic production of
milk and the higher price paid by milk processing companies for raw milk
with low bacterial count. Also the dry cold climatic conditions, clean
housed milking and absence of zero-grazing might have also favoured low
bacterial contamination. It was therefore concluded that the sanitary
quality of milk produced by SHDFs in Lusaka province of Zambia, as far as
bacteria content was concerned was within acceptable standards. There is
need to extend this study to wider locations of milk producing areas in
Zambia.

Conclusion and recommendations

This study found that raw milk produced by SHDFs in Lusaka Province of
Zambia generally conformed to recommended national standards and legal
requirements on TBC and TCC.

Added water found in the milk by small number of farmers indicated the
need for extension education regarding public health concerns, fraudulent
activities and also imposing stiffer penalty on repeated offenders.

There is need to extend this study to wider locations of milk producing
areas in Zambia.

Acknowledgments

The first author wishes to sincerely thank his sponsors The Zambia National
Service Command, Production Branch and Training Branch for the financial and
logistical support rendered towards his MSc study at The University of
Zambia.

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Received 24 July 2015; Accepted 8 August 2015; Published 1 October 2015